What is the purpose of this?

Discussion in 'Irrigation' started by CRUZMISL, Apr 19, 2005.


    CRUZMISL LawnSite Member
    from zone 6
    Messages: 186

    A very elementary question but I have to ask. What does the screw on top of the valve do?

  2. greenworldh20

    greenworldh20 LawnSite Senior Member
    Messages: 659

    you turn it when the client screws you!!!

    uhh, bad joke. it is a manual bleeder screw. give the screw a turn and the valve will open...zone waters.

  3. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    um, no.....you REMOVE it when the client screws you.
  4. aclassic

    aclassic LawnSite Member
    Messages: 178

    careful not to unscrew it too far, i did that once and it came off and the hole filled w/ water before i could get the thing tightened down enough
  5. SWD

    SWD LawnSite Senior Member
    Messages: 988

    You want to know what it does or how it works?

    CRUZMISL LawnSite Member
    from zone 6
    Messages: 186

    Just what is does but if you want to explain how, I'm interested:)
  7. sheshovel

    sheshovel LawnSite Fanatic
    Messages: 5,112

    you use it to turn on the valve manualy,and it will leak when you do so.That's ok cuz it bleeds off pressure in the valve.Otherwize,it opens the valve and closes the valve.turn it open and your water system that's attached to that valve will water without turning on the timer.Close it and it will stop.
  8. Critical Care

    Critical Care LawnSite Bronze Member
    Messages: 1,654

    On some valves, you may notice that the water won't shut off after you close the bleed screw. Briefly closing the flow control adjustment on the valve will stop the water.

    And... some valves can be manually activated by turning their solenoids counterclockwise a quarter of a turn or so while others have small levers or tabs that you press.
  9. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    We've reached the point in this discussion where it might be beneficial to discuss the actuall operation of an electric solenoid valve. The reason for a bleed screw is to manually relieve the pressure from the top of the diaphram so it will "float" and allow water to flow downstream through the valve. The spring above the diaphram is there to help the diaphram seat in the event that the pressure above the diaphram exceeds the pressure below the diaphram (upstream pressure closes the valve while downstream flow provides additional suction to help it close). The port that is opened when a solenoid activates also bleeds the pressure from the top of the diaphram. In MOST valves, this venting is done to the downstream side of a valve. FWIW, in MOST valves, the downstream direction can be determined by the location of the solenoid. The Hunter HPV's and all the jar top type valves are exceptions. Some of the old brass hydraulic valves are also exceptions. If you open a bleed screw, in some valves, the diaphram inverts to a point that it will not close. This is why manually adjusting the flow control or turning off the water and turning it back on will "reset" these valves to a working condition. The valve pictures is a Irritrol/Hardie/Richdel 2400 series valve. The solenoid is designed so that it can be turned aproximately 1/4 turn to open the valve (losening the threads raises the solenoid to a point the plunger no longer makes contact with the exit port, in this instance that port is the flow tube that leads to the effluent side of the valve for "dry" porting of the water.

    That was wordy, but I hoped it helped.
    One other thing, because of their design if you remove this valve and put it in backwards.....it will never close. Almost all automatic irrigation valves share this property. Most have flow arrows to mark influent and effluent sides
  10. sheshovel

    sheshovel LawnSite Fanatic
    Messages: 5,112

    I was trying to keep it as simple as possible for him.Need to know basis and not so as to confuse him or the issue.

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